Rotary internal combustion engine



Jan. 21, 1936.

H. SCHULMAN ROTARY INTERNAL COMBUSTION ENGINE Filed June 22, 1932 2 Sheets-Sheet 1 nvzgxrgg. I

Jan. 21, 1936. H. SCHULMAN ROTARY INTERNAL COMBUSTION ENGINE Filed June 22, 1932 2 Sheets-Sheet 2 Fv NI .aliiillillil!) Patented Jan. 21, 1936 UNITED STATES 2,028,526 v ROTARY INTERNAL COMBUSTION ENGINE Henry Schulman, Pangbourne, England Application June 22, 1932, Serial No. 618,788 In Great Britain June 30, 1931 2 Claim.

This invention relates to rotary internal com-' bustion engines of the type comprising a multicylinder unit consisting of a concentric group of toroidal cylinders, rotatable about their common 5 centre, and a multi-piston unit comprising a corresponding group of pistons, the pistons working within the cylinders and the two units being so rotatable about said common centre and in the same direction as to produce relative re- 10 ciprocation as between each piston and its cylinder. In engines of this type, the various strokes of the internal combustion cycle are performed simultaneously in different cylinders of the group and the relative reciprocation referred to is ob- 15 tained by momentarily holding one of the units during the power stroke of the engine, automatic detent mechanism being provided for this purpose.

The object of the present invention is to pro- 20 vide an improved construction of engine of the type referred to, as will hereinafter appear.

According to the present invention, a rotary internal combustion engine of the type referred to comprises in combination an annular rotary 26 multi-cylinder unit, a co-operating rotary multipiston unit coaxial with the cylinder unit, valve and ignition means operable to occasion explosionsalternately on opposite sides of the pistons, those on one side producing power strokes of 30 the cylinder unit about the common axis of rotation of the units and those on the other side producing auxiliary strokes of the piston unit about said common axis and in the same direction as the strokes of the cylinder unit, the

35 strokes of the piston unit being non-power strokes serving simply to return the two units to their initial relative positions at the commencement of the power stroke of the cylinder unit and means to prevent reverse rotation of each unit during the strokes of the other unit, the cylinder unit having a moment of inertia substantially exceeding that of the piston unit and constituting thereby a flywheel in the engine from which the power of the engine is arranged to be trans- 45 mitted.

Moreover, by arranging that the cylinder unit shall function as a flywheel in the engine and that the power from the engine shall be transmitted from this flywheel, in contrast to the 50 known arrangement wherein both rotating units perform power strokes and 'transmit their rotary thrust in turn through the intermediary oi free-wheel clutch mechanism to a flywheel common to them both and from which the power of 55 the engine is transmitted, the important advan- ,tage is realized of further weight economies and in addition further lessening of complication of parts in the engine: in other words, a lighter, simpler and less expensive engine design is provided and one, moreover, which will be less liable to failure in operation than the prior design referred to. i

It will be understood, of course, that inv an engine in accordance with this invention, the strokes of the piston unit in addition to returning the two units to their initial power stroke firing positions in relation to one another serve at the same time to scavenge the exhaust gases from the previous power stroke and compress the mixture in other cylinders for the next succeeding power stroke.

According to a further feature of the invention, the construction and arrangement of parts may be one in which the cylinder unit comprises a hollow annulus circumferentially slotted completely around the inner periphery of its wall and sub-divided interiorly into a plurality of double-ended cylinders by a series of equally spaced transverse partitions, and the piston unit comprises a group of equally spaced pistons working one within each of said cylinders and mounted upon a carrier member which is external to the cylinder annulus and comprises a part which in a gas tight manner blocks the circumferential slot therein. With such a construction, as will be appreciated, it is readily possible to employ quite a large number of pistons in the engine and correspondingly, of course, a large number of double-ended cylinders, for a gap has not to be interposed in the cylinder wall between opposite ends of the cylinders to accommodate the oscillations of a radial piston rod or its equivalent connecting the double-acting piston .within the cylinder to thepart oi the piston unit exterior to the cylinder, 40

Conveniently and with advantage, the cylinder annulus may be constructed in two opposed complementary halves, with the joint between them lying in the medial plane of the annulus, the two annulus halves being bolted together around the outer circumference of the annulus.

One convenient construction of an aircraft propulsion plant in accordance with the invention will now be described by way oi. example, with reference to the accompanying drawings, of which:-

Figure 1 is an axial view of the unit, with certain of the cylinders broken away to show the pistons;

Figure 2 is a corresponding central longitudinal section through the unit;

Figure 3 is a section through one of the pistons and the ends of two adjacent cylinders; taken along the line 3-3 of Figures 1 and 2;

Figures 4 and 5 are respectively a fragmentary longitudinal section and a fragmentary transverse section through the cylinder-unit showing an alter ative method of construction of the piston-uni Figure 6 is a fragmentary central longitudinal section through the unit showing a modification hereinafter described, and

Figure 7 is a corresponding axial view.

Like reference numerals indicate like parts in the various figures. I

The engine comprises an annular cylinder-unit embodying a group of twelve cylinders, three in each quarter of the unit. The said cylinder-unit is built up of two complementary halves 2 each in the form of a dished annulus. The two halves I, 2 are bolted together by means of closely spaced bolts 3 passing through flanges or lugs 4 cast to receive them around the outer peripheriesof the halves 2. As shown in Figure 2, the annular cavity between the two complementary cylinder halves l, 2 is of circular radial cross-section, and located at regularly spaced intervals around this cavity are a succession of twelve radial partitions 5, bolted in place by means of bolts 5' reaching completely through the cylinder unit. These partitions have a gas-tight fit-with the walls of the cylinder halves and they constitute conjointly with said halves, a group of concentric arcuate cylinders. The unit is revolubly mounted upon a fixed shaft 1.

Revoluble also upon said shaft 1 inthe same direction as the cylinder unit is a disc 8. The outer peripheral margin of this disc is, as clearly shown in Figure 2, inserted between the inner peripheral margins of the two complementary cylinder halves 2, flanges 9 being formed on these margins to extend the surface-area of contact thereof with the margin of the disc 8, it being understood, of course, that there must be no escape of gas past these surfaces, either to or from the interior of the cylinders. To this end, packing means, for example, a series of concentric packing rings I0, are preferably provided between the said surfaces.

Mounted upon the periphery of the disc 8 are a series of twelve pistons |l equally spaced around the circumference of the disc and accommodated each within a cylinder of the cylinder unit.

The cylinder unit is provided with two sets of hollow radial spokes I2, l3 projecting from bosses M, I5 revoluble on the shaft I. The outer ends of these spokes l2, l3 are connected to lateral branches projecting from and integral with the cylinder-unit.

The fixed shaft 1 is hollow and accommodates a supply conduit l6 for carburetted fuel for ignition in the cylinders. This conduit l6 feeds the fuel to an annular induction manifold ll extending around the inner wall of the shaft 1 in the general plane of the boss l5. This manifold has in its outer wall outlet ports |8 which register with an annular port-passage IS in the boss |5. This port-passage IS in turn communicates with the interior, at the inner end, of the hollow spokes l3. At the outer end, the interior of these spokes communicates with fuel passages 20 in the rearward (right hand in Figure 2) lateral branches aforesaid projecting from the cylinder-unit.

In said rearward lateral branches are mounted inlet valves 2| which control the admission of carburetted gas mixture from the passages 20 in the branches to the spaces between the partitions 5 and the-pistons H on either side thereof.

Figures 2 and 3 clearly illustrate the construction in this respect. As shown in these figures, each lateral inlet branch has in it two passages 20 controlled, respectively, by two inlet valves 2|. The gas mixture after passing the valve 2| is admitted, in each case, directly into the cylinder by way of a circumferential inlet port 22.

The lateral branches projecting from the other side of the cylinder unit constitute exhaust branches. They are formed with internal outlet passages 23 leading from circumferential outlet ports 24 in the walls of the cylinders. These outlet passages 23 are separately controlled by exhaust valves 25, and the exhaust gases, after passing the valves 25 enter exhaust manifolds 26. From the ends of these manifolds the gases pass, by way of ports 21, into the interior of hollow propeller blades 28, mounted upon the periphery of the cylinder-unit and provided in their faces, near the extremity of the blade, with-exhaust outlet holes 29 communicating with the atmosphere.

The inlet and exhaust valves 2|, 25 are actuated, of course, in time with one another and with the relative reciprocation of the pistons H and the cylinders within which they work. Their actuating mechanism (not shown) may take any convenient form. For example, it may comprise a system of cam-discs engaging shoes or rollers on the inner end of the valve stems, such for example as shown generally in the patents to Arthur 1,219,795 dated March 20, 1917; Oldham 1,212,100 dated January 9, 1917, etc.

In order to obtain the relative reciprocation of the pistons in their cylinders, the two units are provided with detent means operable to prevent their backward rotation when the unit which is performing its firing stroke is moving forwardly.

The said detent means may take any convenient form. In the form shown, it comprises a disc 30 positioned adjacent one side of the disc 8 and mounted upon and stationary with the shaft 1, and co-operating with the periphery of this disc, 9. series of wedging dogs 32 pivotally mounted upon and carried by the disc 8 and normally held in light rubbing engagement with the periphery of the disc 30 by compression springs 33. A second disc 3| is positioned adjacent the opposite side of the disc 8 and is likewise mounted upon and stationary with the shaft 1. Co-operating with the disc 3| is a second series of wedging dogs 32', pivotally mounted on the inner surfaces of the radial spokes l2 of the cylinder unit and rotating therewith, these dogs 32' having cooperating compression springs 33' and corresponding in construction and operation to the construction and operation of the dogs 32 and springs 33 above referred to.

As will be understood, these two sets of dogs 32 and 32' operate momentarilyto prevent backward rotation of the parts upon which they are mounted, by permitting relative rotation of the I pivots of the dogs and the discs 30 and 3| in one direction only, namely, the direction of rotation of the piston and cylinder units. The dogs immediately resist any tendency to rotation in the opposite direction by wedge-gripping the peripheries of the discs 30, 3|. These peripheries are preferably grooved in a circumferential direction, as shown, to extend their surface-area of engagement with the dogs.

In an alternative construction of the detent means (shown in Figures 6 and. 7), the wedgina dogs 32 may each be mounted upon a pair of pivots 32a, 321;, located one (32a) beyond the other (32b) in a direction radial to the axis of the shaft I, and the radially inner one slightly in front of the outer, as shown in Figure 7, in a circumferential direction opposed to the direction of rotation of the piston disc 3. The outer pivot'32a of these two is mounted, as before, upon the face of the piston disc 8 and the inner pivot is mounted upon the periphery of a pair of discs 32c disposed one on either side of the detent discs 30 and 3i and freely revoluble around the shaft 1 in unison with the piston disc, being rotated around said shaft with this disc by reason of their interconnection with it through the medium of the double-pivoted wedging dogs. With this arrangement, the wedging action of the dogs is highly positive, as will be appreciated, for, upon the commencement of the operative thrust through the dogs from the piston unit or the cylinder unit, as the case may be, the dogs immediately pivot slightly about their inner pivots and at once bite on to the grooved peripheries of the discs 30 and 3i with which they function. y

The engine also comprises a magneto 34 and'a lubricating pump 35, these mechanisms being driven by a gear wheel 35 rotatable with the boss l5 and meshing with pinions 31, 33, fast, respectively, with the spindles of the magneto 34 and pump 35.

The ignition means of the engine comprises, as usual, sparking plugs. These plugs. 33 are fitted in the cylinder walls close to the partitions 5 which separate the cylinders. The electric leads from the plugs are led down tothe interior of the fixed shaft 1 by way of the hollow spokes i2 and leading-in tubes 40 fromxwhence they are led along said shaft 1 to the'dlstributor of the magneto. The means fon'securing the ignition of the compressed charges at the right moment'is not indicated, but any convenient ignition means may be employed so as to ignite the charges in the cylinders when the cylinder-units and pistonunits come into their proper working positions. The ignition system may be either a system of coil ignition or a system of magneto ignition. In the latter event, the magneto 34 would, as usual, incorporate a distributor connected up in an appropriate manner, well understood in the art, to the several sparking plugs'33. If, on the other hand, a system of coil ignition be employed, the magneto 34 would be substituted by a suitable generator which, as usual would supply current to a battery, in turn wired up to the plugs 39 through the intermediary of an induction coil, make-and-break device, and distributor, the generator preferably, moreover, being provided with a direct connection to the induction coil by-passing the battery. As suggestive of a form of ignition system which may be employed, attention is invited to Figure 6 of the patent to Edqvist, No. 1,108,980 dated September 1, 1914.

The engine operates on the principle of the four-stroke cycle. 'This will be clear from the following description of the operation of the engine, carrying one of the cylinders, A, completely through the four strokes of the cycle.

It will be assumed that the cylinder unit is just about to commence to stroke, against the reaction of the piston unit, which during the stroke of the cylinder unit will be prevented from backward rotation by the detent action of the wedging dogs 32 and the disc 30. At this juncture, there is a charge of combustible mixture in the forward part a of the cylinder A compressed in readiness for firing, this \charge having been drawn into the said part of the cylinder during the previous stroke of the cylinder unit and having been compressed therein during the stroke of the piston unit following .that previous stroke of the cylinder unit. Firing now takes place of the said compressed charge in the forward part a of cylinder A, with the result that the cylinder unit moves forward against the reaction of the piston unit as described above. During this stroke of the cylinder unit, a charge of combustible mixture, previously drawn into the rear part (11 of,

the cylinder A during the stroke of thepistonufiit immediately preceding the curreniestroke of the cylinder unit, becomes cgrnpr'ssed in readiness for firing to move theapiston unit forward through its stroke, whicii'now occurs, the cylinder unit being prevented this time from backward rotation by the 'wedging dogs 32 co-operating with disc 3i. At the same time, that is to say, during the stroke of the cylinder unit and the expansion of the gases of combustion in said part a of cylinder A, the products of combustion of the said preceding stroke of the piston unit in the rear part hr of the next cylinder B of the unit become scavenged out of this part bl while in'part b of said cylinder B a fresh charge of combustible gases is drawn in, in readiness to be compressed during the next stroke of the piston unit. During the stroke of the cylinder unit, there takes place, therefore, on the rear side of the partition or cylinder end 5 a firing and expansion of the power-stroke gases of combustion and on the forward side a scavenging of the products of combustion of the non-power stroke gases of combustion of the last preceding stroke of the piston unit. At the same time, there takes place on the rear side of the cylinder end 5 of the adjacent cylinder B a suction in of a fresh power-stroke charge of combustible gases, to be compressed during the next stroke of the piston unit, and on the forward side a compression of the non-power stroke charge previously drawn in during said preceding stroke of the piston unit. This cycle. involving during alternate strokes of the cylinder unit, compression at the rear end of the cylinder and firing at the forward end and during the intervening strokes, scavenging at the rear end of the cylinder and suction at the forward end, and correspondingly during alternate strokes of the piston unit, firing at the rear end of the cylinder and scavenging at the forward end and during the intervening strokes, suction at the rear end and compression at the forward end, is repeated, as will be appreciated, a number of times per revolution of the engine equal to one half the total number of cylinders, that is to say in the engine shown, six times.-

As will be seen from the accompanying drawings, the cylinder unit is considerably more massive than the piston-unit. This is an important feature, for the excess of weight in the cylinderunit over the piston-unit provides a flywheel effeet in the rotation of the parts, with the result that if the said excess of weight is sumcient, the rotation of the cylinder-unit may be rendered substantially continuous, the piston-unit performing its reciprocation relatively to the cylinder-unit by moving alternately faster and slower than that unit.

Referring now to Figures 4 and 5, the modified construction of piston-unit illustrated in these figures is one in which the piston disc 8 is formed with radial projections 4| at each piston positioned around its periphery. These projections 4| are integral with the disc and in efiect constitute in'each case a central section of the piston, the two side sections 42 of which are of cylindrical contour and are bolted on to the opposed faces of the projection'by means of bolts 42'. The

composite piston thus produced may be fitted,

What I claim and desire to secure by Letters Patent is:-

1. A rotary internal combustion engine of the type referred to comprising in combination an annular rotary multi-cylinder unit, a co-operating rotary multi-piston unit co-axial with the cylinder unit, valve and ignition means operable to occasion explosions alternately on opposite sides of the pistons, those on one side producing power strokes of the cylinder unit about the common axis of rotation of the units and those on the other side producing auxiliary strokes of the piston unit about said common axis and in the same direction as the strokes of the cylinder unit, the

auxiliary strokes of the piston unit serving to return the two units to their initial relative positions at the commencement of the power stroke 01' the cylinder. unit and means comprising stationary reaction members cooperating with unidirectional clutch elements on the rotating units to prevent reverse rotation of each unit during the strokes of the other unit, the cylinder unit having a moment of inertia substantially exceeding that of the piston unit and constituting thereby a flywheel in the engine from which the power of the engine is arranged to be transmitted.

2. A rotary internal combustion engine of the type referred to comprising in combination an annular rotary multi-cylinder unit, a co-operat ing rotary multi-piston unit coaxial with the cylinder unit and valve and ignition means operable to occasion explosions alternately on opposite sides of the pistons, those'on one side producing power strokes of the cylinder unit about the common axis of rotation of the units and those on the other side producing auxiliary strokes of the piston unit about said common axis and in the same direction as the strokes of the cylinder unit, the auxiliar strokes of the piston unit serving to return the two units to their initial relative positions at the commencement of the power stroke of the cylinder unit. detents on each unit co-operating with fixed circular 'reaction members concentric with the units, to prevent reverse rotation of each unit during the strokes of the other unit, the cylinder unit having a moment of inertia substantially exceeding that of the piston unit and constituting thereby a flywheel in the engine from which the power of the engine is arranged to be transmitted.

HENRY SCHULMAN. 

